1. Field of the Invention
The present invention relates to a trailer coupling determination apparatus and to a trailer coupling determination method for determining whether or not a trailer is coupled with a tractor.
2. Description of Related Art
Since the gross weight of a tractor for towing a trailer greatly changes depending on whether or not the trailer is coupled, the ways in which the engine, the transmission, the brake or the like are controlled may be changed accordingly, for example. Thus, as disclosed in Japanese Patent Application Laid-open Publication No. H11(1999)-165623, a technique for determining whether or not a trailer is coupled with a tractor is proposed, which is based on a characteristic of increasing in control pressure for controlling a service brake (regular brake) of the trailer.
Conventional techniques, however, determine whether a trailer is coupled or not based on the characteristic of increasing in control pressure for controlling a service brake of the trailer, and so the determination for trailer coupling cannot be made before the actual start of tractor travel. If the engine or the like were controlled at the start of tractor travel while towing a trailer as if the trailer were not coupled, the tractor may not start smoothly due to insufficient driving power, for example.